DRAGraces: A pipeline for the GRACES high-resolution spectrograph at Gemini

TL;DR

DRAGraces is a user-friendly, automated data reduction pipeline for the GRACES spectrograph at Gemini, producing spectra comparable in quality to the more complex OPERA pipeline, with differences in ease of use and extraction precision.

Contribution

The paper introduces DRAGraces, a new, straightforward pipeline for reducing GRACES spectra, offering an alternative to the existing OPERA pipeline with comparable results.

Findings

DRAGraces produces spectra with resolution R~52.8k and 36.6k in high and low modes.

Both pipelines deliver similar wavelength solutions and signal-to-noise ratios.

DRAGraces is easier to use and less sensitive to parameter tweaks.

Abstract

This paper describes the software DRAGraces (Data Reduction and Analysis for GRACES), which is a pipeline reducing spectra from GRACES (Gemini Remote Access to the CFHT ESPaDOnS Spectrograph) at the Gemini North Telescope. The code is written in the IDL language. It is designed to find all the GRACES frames in a given directory, automatically determine the list of bias, flat, arc and science frames, and perform the whole reduction and extraction within a few minutes. We compare the output from DRAGraces with that of OPERA, a pipeline developed at CFHT that also can extract GRACES spectra. Both pipelines were developed completely independently, yet they give very similar extracted spectra. They both have their advantages and disadvantages. For instance, DRAGraces is more straightforward and easy to use and is less likely to be derailed by a parameter that needs to be tweaked, while OPERA offers a more careful extraction that can be significantly superior when the highest resolution is required and when the signal-to-noise ratio is low. One should compare both before deciding which one to use for their science. Yet, both pipelines deliver a fairly comparable resolution power (R~52.8k and 36.6k for DRAGraces and R~58k and 40k for OPERA in high and low-resolution spectral modes, respectively), wavelength solution and signal-to-noise ratio per resolution element.